Questions

Here we are initalising the function pointer p to the address of the function fun(). But during this initialisation the function has not been defined. Hence an error.

To eliminate this error add the prototype of the fun() before declaration of p, as shown below:

extern int fun();    or simply  int fun();

Let the missing numbers be x, y, a and b

x + y = 8 ---- (1)
a - b = 6 ---- (2)
x + a = 13 --- (3)
y + b = 8 ---- (4)

2x + a + y = 21 --- From (1 & 3)
a + y = 14 ----  From (2 & 4)

Substitute (2 & 4) in (1 & 3)

2x + 14 = 21
2x = 7
x = 3.5

From (1) ---> 3.5 + y = 8
=> y = 8 - 3.5 = 4.5

a + y = 14 => a = 14 - y = 14 - 4.5 => a = 9.5
From (4) ---- y + b = 8 => b = 8 - y = 8 - 4.5 = 3.5

Hence,
x = 3.5
y = 4.5
a = 9.5
b = 3.5

23 hrs, 56 minutes and 4.9 seconds

One atomic mass unit (AMU) is equal to the one-twelfth the mass of one carbon-12 atom.

The P atom needs five orbitals to form the five P-Cl bonds. It has a 3s and three 3p orbitals, so it must use one of its 3d orbitals to form the fifth bond. These orbitals are hybridized to form five sp3d orbitals that just happen to point in the right directions to form a trigonal bipyramid.

The oxygenated blood  flows through pulmonary veins then leaves the lungs, which return it to the left heart, completing the pulmonary cycle.

Indore city was adjudged as India's Cleanest City for the third consecutive year as per Swachh Survekshan 2019.